HEAD High Energy Astrophysics Division


Newsletter No. 98, June 2011

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13. The International X-ray Observatory (IXO) - Michael Garcia (CfA)

Over the past few months, significant changes have occurred in the IXO
mission. The decadal rankings and NASA´s constrained out-year resources
have led ESA to conclude that none of the three US-partnered L1 mission
concepts under consideration, including IXO and LISA, were feasible within the
Cosmic Vision schedule. Consequently, ESA has begun a rapid definition
effort to identify science goals and mission concepts that can be implemented
as an ESA-led mission launching in the early 2020´s. The total cost to ESA will
be about 800M Euro, with selection of one or two concepts for further study in
February 2012.

The ESA X-ray L1 mission concept, dubbed 'Athena,' will carry two telescopes,
one with a Wide Field Imager at the focus and the other with an imaging X-ray
Micro-calorimeter Spectrometer. A future minority role for NASA within this
ESA-led mission may be possible, and ESA has engaged NASA/HQ in order to
consider the best approach and timescale for such contributions. There is US
participation on the Athena Science Definition Team, Instrument Team, and
associated Science Teams. A community workshop to present Athena
and its science capabilities took place on June 14-15, 2011, at MPE

In the light of the ESA decision, NASA HQ is redirecting NASA efforts in the
context of the decadal survey recommendations. Those recommendations
include continuing the IXO technology development efforts and considering
possible down-scopes to the full IXO mission. Efforts in both areas
continue. The mirror team recently reached a milestone in breaking the 10
arcsec (HPD) barrier with a pair of mounted and aligned mirrors in an X-ray
test. Meanwhile, the calorimeter team has fabricated the first 32x32 arrays with
the required wiring and size for IXO. The mission design team has begun
looking at lower cost and lower mass versions of IXO.

We expect that after the ESA L1 decision is announced, NASA will ask the NRC
for input on possible NASA participation in ESA missions.

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